Static conductive coating as well as preparation method and automobile application thereof

Abstract

The embodiment of the invention provides a static conductive coating and a preparation method and automobile application thereof. The static conductive coating comprises the following raw materials in parts by weight: 0.5-2 parts of a dispersing agent; 3-4 parts of a carbon nano tube; 0.2 to 0.6 part of a defoaming agent; 0.1 to 2 parts of a viscosity reducer; 1-5 parts of modified conductive titanium dioxide; and 1-5 parts of acrylic resin. According to the static conductive coating, the preparation method thereof and the automobile application provided by the embodiment of the invention, the static conductive coating is more uniformly dispersed in acrylic resin through modification, and can be more easily combined with a dispersing agent and a carbon nanotube through surface modification, and the two are in close contact, so that more conductive paths are obtained, and layered precipitation is not easy to occur; and the conductivity, the mechanical property, the whiteness and the dispersity are all improved.

Description

Technical Field

[0001] This application belongs to the technical field of coatings, and particularly relates to an antistatic coating, a preparation method thereof, and automotive applications. Background Art

[0002] With the rapid development of the automotive industry, the application of non-metallic parts in automobiles has been increasing. However, due to the non-conductivity of non-metallic parts, a large number of workpieces rely on manual painting. Manual painting has problems such as great randomness and poor color matching with the electrostatic painting of the whole vehicle, resulting in a high defective rate. As the direct manifestation of the quality of automobiles, automotive topcoats are particularly expensive in high-end automobiles. To improve the utilization efficiency of topcoats, electrostatic spraying technology has become a development trend. Electrostatic spraying uses a high-voltage electrostatic field to evenly spray the topcoat on the surface of specified components under the action of the electric field, and its utilization efficiency can reach 50% to 70%, while the efficiency of traditional air spraying is only 20% to 30%. To achieve electrostatic spraying, the components must have conductive or antistatic properties, and usually require their surface resistance to be less than 10 9 Ω / □. Due to their excellent conductivity, metal materials can be directly electrostatically sprayed. However, most non-metallic components are insulating materials, and their surface resistance is usually greater than 10 14 Ω / □. Therefore, to achieve electrostatic spraying of non-metallic components, they must be made into antistatic materials or covered with antistatic coatings on the surface.

[0003] Currently, industrial antistatic coatings mainly use doped conductive coatings. The commonly used conductive media in such coatings include metal powders (such as copper, nickel, silver powders), conductive carbon powders, graphene, carbon nanotubes, conductive titanium dioxide, and conductive mica powder, etc. Among them, the use of metal powders is restricted due to their high specific gravity, expensive raw materials, and easy oxidation. As non-carbon-based raw materials, conductive mica powder and conductive titanium dioxide are the first choices for light-colored antistatic materials, but domestic products have obvious defects in whiteness, fineness, and resistance value, and have a large addition amount and high price, which limits their application. Conductive carbon powder has a deep color and strong coloring power, and is mainly used in black and dark conductive / antistatic coatings, but requires the topcoat to have a certain covering power. The usage amount of conductive carbon black needs to reach more than 10wt.%, which results in the paint color being too deep and difficult to meet the requirements of automotive primer.

[0004] In summary, although electrostatic spraying technology has significant advantages in improving the utilization efficiency of topcoats, the antistatic treatment of non-metallic components in automobiles still faces many challenges, and it is necessary to further research and improve antistatic coatings to meet the high standards of the automotive industry. Summary of the Invention

[0005] In view of this, the embodiments of this application provide an antistatic coating, a preparation method thereof, and automotive applications to solve the technical problem that the existing coatings are difficult to meet the antistatic treatment requirements of non-metallic components in automobiles.

[0006] In a first aspect, embodiments of the present application provide an antistatic coating, comprising the following raw materials in parts by weight:

[0007] Dispersant: 0.5 - 2 parts;

[0008] Carbon nanotubes: 3 - 4 parts;

[0009] Defoamer: 0.2 - 0.6 parts;

[0010] Viscosity reducer: 0.1 - 2 parts;

[0011] Modified conductive titanium dioxide: 1 - 5 parts;

[0012] Acrylic resin: 1 - 5 parts.

[0013] In some embodiments, the dosage ratio of the carbon nanotubes to the dispersant is (3 - 4):1.

[0014] In some embodiments, the carbon nanotubes are multi-walled carbon nanotubes.

[0015] In some embodiments, the dispersant is an HNBR dispersant.

[0016] In some embodiments, the viscosity reducer comprises an organic polymer with an inorganic affinity group (such as a hydroxyl group), wherein the viscosity of the viscosity reducer is 200 - 300 cps / 25°C and the density is D25≥1.06 g / cm 3 .

[0017] In some embodiments, the preparation method of the dispersant comprises:

[0018] Formulating a nitrile rubber solution and providing hydrogen;

[0019] Preheating the nitrile rubber solution to 100°C - 160°C to obtain a preheated nitrile rubber solution, and preheating the hydrogen to 120°C - 160°C to obtain preheated hydrogen;

[0020] Simultaneously introducing the preheated nitrile rubber solution and the preheated hydrogen into a tubular reactor for reaction to obtain the dispersant.

[0021] In some embodiments, the preparation method of the modified conductive titanium dioxide comprises:

[0022] Providing a silane coupling agent, an organic solvent, and conductive titanium dioxide;

[0023] Mixing the silane coupling agent and the organic solvent to obtain a mild solution;

[0024] Add conductive titanium dioxide to the above mixed solution, and under stirring, control the temperature at 70 - 100 °C, reflux for 100 - 150 min, cool down to room temperature for discharging, and obtain an intermediate after filtration and drying;

[0025] Grind the intermediate to obtain the modified conductive titanium dioxide.

[0026] In some embodiments, the particle size of the modified conductive titanium dioxide is less than 40 nm.

[0027] In some embodiments, the viscosity reducer includes one of polyvinyl alcohol, glycerol, and boric acid.

[0028] In some embodiments, the antistatic coating further includes 90 - 100 parts by weight of a low-polarity solvent.

[0029] In some embodiments, the defoamer includes one of dimethyl silicone oil, polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycerol ether.

[0030] In some embodiments, the viscosity of the antistatic coating ≤ 200 cps, the volume resistivity ≤ 10 5 ohm·cm, and the fineness ≤ 10 μm.

[0031] In a second aspect, an embodiment of the present application provides a method for preparing an antistatic coating, including:

[0032] Provide the raw materials in parts by weight of the antistatic coating according to any one of claims 1 to 8 and 90 - 100 parts by weight of a low-polarity solvent;

[0033] Fully mix the above raw materials in parts by weight with the low-polarity solvent to obtain the antistatic coating.

[0034] In a third aspect, an embodiment of the present application further provides an application of the antistatic coating in an automobile, and the antistatic coating is applied to the paint coating of an automobile.

[0035] The antistatic coating, its preparation method and application provided by the embodiments of the present application have a formulation cost much lower than that of the conductive coating prepared by using conductive titanium white and conductive mica as conductive media, and are 5 - 6 yuan / kg lower than the conductive coating prepared by using the commonly used conductive carbon black as a conductive medium in the current market. Moreover, the coating has good adhesion to the substrate, good compatibility with color paint and varnish, good overall film appearance, and excellent electrostatic spraying and painting performance;

[0036] Compared with the prior art, the preparation process of the present invention is simple, has a low VOC content, good adhesion to the substrate, a low resistance value, and can be made very white in color (the coloring power of the conductive carbon nanotubes is low, and it is combined with conductive titanium dioxide), and has excellent water resistance after being matched with the topcoat; it can meet the electrostatic coating application, improve the painting of the matching color paint and varnish, and reduce the environmental pollution caused by paint mist.

[0037] The modified conductive titanium dioxide is made to disperse more uniformly in the acrylic resin through modification, and through surface modification, it can also be more easily combined with the HNBR dispersant and carbon nanotubes. The contact between the two is close, resulting in more conductive paths, not easily undergoing delamination and precipitation, and improving the conductivity, mechanical properties, whiteness, and dispersibility. Brief Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0039] Figure 1 It is a schematic flow chart of the preparation method of the antistatic coating provided by the embodiments of the present application. Detailed Embodiments

[0040] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the embodiments of the present application can also be implemented in other embodiments without these specific details. In other cases, the detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the embodiments of the present application.

[0041] It should also be understood that the term "and / or" used in the specification and claims of the embodiments of the present application refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0042] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0043] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of the present application.

[0044] In addition, in the description of the specification and the appended claims of the embodiments of the present application, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

[0045] The reference to "some embodiments" or "some embodiments" etc. described in the specification of the embodiments of the present application means that in one or more embodiments of the embodiments of the present application, specific features, structures or characteristics described in connection with that embodiment are included. Thus, statements such as "in some embodiments", "in some embodiments", "in other some embodiments", "in still other some embodiments" etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. Terms such as "include", "comprise", "have" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way. "Plurality" means two or more.

[0046] The embodiments of the present application provide an antistatic paint, which comprises the following raw materials in parts by weight:

[0047] Dispersant: 0.5 - 2 parts;

[0048] Carbon nanotubes: 3 - 4 parts;

[0049] Defoamer: 0.2 - 0.6 parts;

[0050] Viscosity reducer: 0.1 - 2 parts;

[0051] Modified conductive titanium dioxide: 1 - 5 parts;

[0052] Acrylic resin: 1 - 5 parts.

[0053] The antistatic coating provided by the embodiments of the present application has better conductivity. Due to the high conductivity of carbon nanotubes, compared with conductive mica (flake-shaped) and conductive carbon black (granular), the one-dimensional structure of carbon nanotubes can form a three-dimensional continuous conductive network at a low addition amount (3-4 parts), with higher conductivity. The modified conductive titanium dioxide combines with carbon nanotubes to fill the gaps in the conductive path and reduce the surface resistivity. The acrylic resin provides excellent adhesion and wear resistance, and the reinforcing effect of carbon nanotubes can improve the coating hardness. The low filler addition amount (total conductive filler ≤ 9 parts) allows the coating to be thinner (such as 10-20 μm), reducing the load on the substrate. Traditional conductive carbon black coatings can only be black, while the modified conductive titanium dioxide is white or light-colored, and a variety of appearances can be achieved through color matching to meet the aesthetic requirements of automotive paint coatings. Reducing the dependence on carbon black: High addition amounts (usually 10-30 parts) of conductive carbon black are required to achieve the same conductivity, while the low usage amount of carbon nanotubes reduces the raw material cost (although the unit price is high, the total amount is small). Compared with some conductive mica (containing metal coatings), titanium dioxide and carbon nanotubes are more environmentally friendly.

[0054] In some embodiments, the antistatic coating further includes 90-100 parts by weight of a low-polarity solvent. In applications, the low-polarity solvent includes, but is not limited to, xylene, n-hexane, cyclohexane, toluene, dichloromethane, etc. In a preferred embodiment, the low-polarity solvent is xylene. By reasonably selecting and using the low-polarity solvent, the chemical reaction efficiency or material processing performance can be effectively improved, while ensuring safety and environmental protection.

[0055] The comparison table of the antistatic coating provided by the embodiments of the present application and the traditional conductive mica / carbon black coating is as follows:

[0056]

[0057] In applications, the role of the dispersant is to ensure the uniform dispersion of carbon nanotubes and modified conductive titanium dioxide in the system, prevent agglomeration, and improve the continuity of the conductive network. Carbon nanotubes are prone to agglomeration due to van der Waals forces. The dispersant can improve its compatibility with the resin and increase the conductivity. As the core conductive material, carbon nanotubes form a three-dimensional conductive network through a one-dimensional tubular structure, providing high conductivity at a low addition amount. It has a large specific surface area and a high aspect ratio, and a small amount can build an efficient conductive path. The defoamer is used to eliminate the bubbles generated during the production or construction of the coating, avoid pinhole defects after the coating is cured, and improve the coating density. The viscosity reducer adjusts the viscosity of the coating, improves the construction leveling property, ensures uniform film formation of the coating, and reduces energy consumption (such as easier atomization during spraying). The surface of the modified conductive titanium dioxide is coated with a conductive substance (such as antimony tin oxide) to assist carbon nanotubes in constructing a conductive network. It has both covering power and light-color characteristics, solving the limitation that traditional conductive carbon black can only provide black. The acrylic resin serves as a film-forming matrix, providing mechanical properties such as the adhesion, hardness, and weather resistance of the coating, and having good compatibility with the conductive filler.

[0058] In the application, the carbon nanotubes are multi-walled carbon nanotubes. Compared with single-walled carbon nanotubes, multi-walled carbon nanotubes have more stable electrical conductivity. Multi-walled carbon nanotubes are formed by curling multiple layers of graphene, and each layer is combined by van der Waals forces. This multi-layer structure makes its electrical conductivity more stable. Even if the outer layer is damaged, the inner layer can still maintain the conductive path. Multi-walled carbon nanotubes are less sensitive to impurities and defects, and their electrical conductivity is less affected by the environment. The multi-layer structure of multi-walled carbon nanotubes endows them with higher mechanical strength and toughness, and can effectively enhance the impact resistance and wear resistance of the coating. The diameter of multi-walled carbon nanotubes is larger (usually 10 - 30 nm), and it is easier to disperse in the resin matrix than single-walled carbon nanotubes (1 - 2 nm), reducing the agglomeration phenomenon. The surface energy of multi-walled carbon nanotubes is lower, and it is easier to be compatible with matrix materials such as acrylic resin, reducing the usage amount of dispersants.

[0059] In some embodiments, the dispersant is the abbreviation dispersant of HNBR (Hydrogenated Nitrile Butadiene Rubber), which is a special dispersing aid for the hydrogenated nitrile rubber system. HNBR is a high-performance rubber material with excellent oil resistance, heat resistance, chemical resistance and mechanical properties, and is widely used in the fields of automotive, petroleum, aerospace, etc. HNBR has excellent wetting and dispersing ability. The cyano group (—CN) in the HNBR molecular chain has strong polarity and can form hydrogen bonds or van der Waals forces with the functional groups (such as hydroxyl groups, carboxyl groups) on the surface of carbon nanotubes (CNTs) and modified conductive titanium dioxide, effectively wetting the surface of the filler and reducing agglomeration. The long-chain structure of HNBR can form a physical barrier around the filler to prevent the particles from re-aggregating and maintain the dispersion stability. HNBR has good compatibility with acrylic resin, avoiding coating defects (such as shrinkage holes, fisheyes) caused by the separation of the dispersant from the resin phase. HNBR itself has elastomer characteristics, which can improve the flexibility and impact resistance of the coating and make up for the brittleness of acrylic resin. The polar groups of HNBR promote the electron transfer between carbon nanotubes and the resin, reduce the interfacial contact resistance, and enhance the continuity of the conductive path. Under the action of shear force (such as stirring, spraying), HNBR helps the carbon nanotubes to align in a specific direction to form a three-dimensional conductive network, reducing the percolation threshold (conductive at low addition amounts). The rheological properties of HNBR help to reduce the viscosity of the coating, improve the leveling property during spraying or brushing, and avoid orange peel or bubbles on the coating.

[0060] In some embodiments, the preparation method of the dispersant includes:

[0061] Form a nitrile rubber solution and provide hydrogen;

[0062] Preheat the nitrile rubber solution to 100°C to 160°C to obtain the preheated nitrile rubber solution, and preheat hydrogen to 120°C to 160°C to obtain the preheated hydrogen; preheat the nitrile rubber solution and hydrogen to 100°C to 160°C and 120°C to 160°C respectively to ensure that the reactants reach the activation temperature when entering the reactor, accelerate the hydrogenation reaction rate, and at the same time reduce the temperature fluctuation in the reactor. The tubular reactor is a fully enclosed system to avoid the leakage of solvents (such as toluene or acetone in the nitrile rubber solution) and hydrogen, reduce VOC emissions and explosion risks; after preheating, hydrogen is fully mixed with the NBR solution to increase the solubility of hydrogen in the liquid phase, reduce the waste of unreacted hydrogen, and recycle the residual hydrogen through the circulation system to reduce the raw material cost.

[0063] Simultaneously introduce the preheated nitrile rubber solution and the preheated hydrogen into the tubular reactor, and react to obtain the dispersant. Through the continuous hydrogenation process of the tubular reactor, combined with precise temperature control and hydrogen preheating, the efficient, environmentally friendly and large-scale production of the HNBR dispersant is realized. The obtained dispersant has excellent dispersing ability, heat resistance and chemical stability, and can meet the dual requirements of high-end antistatic coatings for performance and cost.

[0064] In the application, preheat the nitrile rubber solution to 100°C to 160°C, specifically, the nitrile rubber solution can be preheated to any value within the range of 110°C to 160°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, etc. Preheat hydrogen to 120°C to 160°C, specifically, hydrogen can be preheated to any value within the range of 120°C to 160°C, such as 120°C, 130°C, 140°C, 150°C, 160°C, etc.

[0065] In the application, maintain the pressure in the tubular reactor at 3.0 mpa.g to 10.0 mpa.g and the temperature at 120°C to 160°C. The material flows through the catalyst bed for the hydrogenation reaction to obtain the system after the hydrogenation reaction, and separate the system after the hydrogenation reaction to obtain the hydrogenated nitrile rubber.

[0066] In some embodiments, the dosage ratio of carbon nanotubes to the dispersant is (3 - 4):1. The role of the dispersant is to prevent particle agglomeration by reducing the surface tension or forming a protective layer, thereby improving the dispersibility of solid particles in the liquid medium. For carbon nanotubes, due to their high aspect ratio and large specific surface area, agglomeration is likely to occur, which will significantly affect their electrical conductivity and other functional characteristics. When the ratio of the dispersant to carbon nanotubes is set to 1:(3 - 4), the relationship between the dispersion demand and the economic cost can be effectively balanced. Excessive dispersant not only increases the cost but may also have a negative impact on other properties of the coating, such as an increase in viscosity and a decrease in coating hardness; while too little dispersant cannot sufficiently inhibit the agglomeration tendency of carbon nanotubes. Therefore, this ratio can avoid resource waste while ensuring good dispersion effects.

[0067] In applications, as a one-dimensional nanomaterial, carbon nanotubes have an extremely high aspect ratio and excellent electrical conductivity. When the addition amount is 3 - 4 parts, a continuous and efficient conductive network can be formed in the matrix. This network structure is crucial for achieving the overall conductivity of the coating. An appropriate ratio of the dispersant helps to ensure that each carbon nanotube can be evenly dispersed into the matrix, thereby maximizing its conductive potential.

[0068] In some embodiments, the viscosity reducer includes an organic polymer with inorganic affinity groups (such as hydroxyl groups), where the viscosity of the viscosity reducer is 200 - 300 cps / 25°C, and the density is D25 ≥ 1.06 g / cm 3 . The core function of the viscosity reducer is to reduce the viscosity of the target system, thereby improving its fluidity and processing performance. When the viscosity of the viscosity reducer itself is controlled within the range of 200 - 300 cps, it can ensure that when it is added to a high-viscosity system, it will not affect the overall effect due to its too high viscosity. On the contrary, a lower and moderate viscosity helps the viscosity reducer to be quickly and evenly dispersed in the system, quickly play its role, and effectively reduce the viscosity of the entire system. The density of the viscosity reducer is designed to be D25 ≥ 1.06 g / cm 3 , and this value is usually close to or slightly higher than the density range of many common media in industrial applications. Through this density matching, the viscosity reducer can more easily achieve good compatibility with the target system during the mixing process, avoiding stratification or sedimentation phenomena caused by too large a density difference.

[0069] In an application, the viscosity reducer includes one of polyvinyl alcohol, glycerol, and organic boric acid. Polyvinyl alcohol is a water-soluble polymer with a wide range of uses, having good film-forming properties and solubility. It can change the rheological properties of the system by forming a stable colloidal structure, thereby achieving the effect of reducing viscosity. Glycerol, that is, propanetriol, is known for its strong hygroscopic ability. This property allows it to absorb moisture from the surrounding environment, thereby affecting the intermolecular forces within the liquid system and achieving the purpose of reducing viscosity. Organic boric acid can act as a crosslinking promoter under specific conditions, forming a network structure by reacting with hydroxyl groups or other functional groups present in the system, thereby regulating the flow behavior of the entire system.

[0070] In some embodiments, the defoamer includes one of dimethyl silicone oil, polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycerol ether. Dimethyl silicone oil becomes an efficient defoamer due to its extremely low surface tension and water-insoluble characteristics. It can quickly penetrate into the foam film, reducing the local surface tension and causing the foam to break. As a polymer surfactant, polyethylene glycol helps to form a stable oil-in-water emulsion in the silicone oil defoamer, thereby improving the stability and efficiency of the defoamer. In some embodiments, the acrylic resin is a polymer prepared by copolymerizing acrylate esters, methacrylate esters, and other olefinic monomers.

[0071] In some embodiments, the preparation method of the modified conductive titanium dioxide includes:

[0072] Providing a silane coupling agent, an organic solvent, and conductive titanium dioxide;

[0073] Mixing the silane coupling agent and the organic solvent to obtain a mixed solution;

[0074] Adding conductive titanium dioxide to the mixed solution, and under stirring, controlling the temperature at 70 - 100 °C, refluxing for 100 - 150 min, cooling to room temperature for discharging, filtering and drying to obtain an intermediate;

[0075] Grinding the intermediate to obtain the modified conductive titanium dioxide. The operating steps of this method are relatively simple, mainly including conventional chemical engineering operations such as mixing, refluxing, filtering, and drying, and are easy to realize industrial production. Especially the reflux treatment within the temperature range of 70 - 100 °C not only ensures the effective grafting of the silane coupling agent but also avoids side reactions or material damage that may be caused by high temperatures. At the same time, the entire process does not require complex equipment support, reducing production costs and technical thresholds.

[0076] In applications, silane coupling agents are bifunctional compounds. One end can react with the hydroxyl groups on the surface of inorganic materials (such as conductive titanium dioxide), and the other end can chemically or physically interact with the organic polymer matrix. Therefore, by introducing silane coupling agents onto the surface of conductive titanium dioxide, a strong chemical bonding can be formed between the inorganic filler and the organic matrix, thereby significantly enhancing the interfacial bonding strength between the two. This enhanced bonding strength helps to improve the overall mechanical properties, electrical properties, and durability of the composite material. During the preparation of composite materials, the agglomeration of inorganic fillers is a common problem, which can seriously affect the performance of the final product. By surface-modifying conductive titanium dioxide with silane coupling agents, a thin and uniform organic coating layer can be formed on its surface, reducing the van der Waals forces and other attractive forces between particles, thus effectively preventing particle agglomeration. In addition, the modified conductive titanium dioxide is more easily dispersed in organic solvents or polymer matrices, ensuring the uniformity and stability of the internal structure of the material. Conductive titanium dioxide itself has good electrical conductivity and optical properties, but untreated particles may have a decrease in conductive efficiency due to surface defects or oxidation states. The modification process of silane coupling agents can not only repair these surface defects but also optimize the electron transport path on the particle surface, thereby improving the actual conductive ability of conductive titanium dioxide. This is particularly important for manufacturing high-performance conductive composite materials.

[0077] In applications, silane coupling agents include but are not limited to KH-550 (3-aminopropyltriethoxysilane), KH-560 (3-glycidoxypropyltrimethoxysilane), KH-570 (3-methacryloxypropyltrimethoxysilane), KH-792 (N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane), DL-602 (vinyltrimethoxysilane), KH-171 (vinyltriethoxysilane), KH-580 (mercaptopropyltriethoxysilane), KH-590 (3-chloropropyltrimethoxysilane), etc. In applications, organic solvents include but are not limited to methanol, ethanol, acetone, isopropanol, tetrahydrofuran, and dichloromethane, etc. The above organic solvents are inexpensive and easily available, and are easy to remove during the reaction, which is beneficial to environmental protection. In applications, the reaction temperature is 70-100 °C, specifically, it can be any value within the range of 70-100 °C, such as 70 °C, 70 °C, 70 °C, 70 °C, etc. The reflux time is 100-150 min, specifically, it can be any value within the range of 100-150 min, such as 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, etc.

[0078] In some embodiments, the particle size of the modified conductive titanium dioxide is less than 40 nm. When the particle size of the conductive titanium dioxide is reduced to the nanoscale, especially when it is less than 40 nm, its optical properties will change significantly. According to the literature, when the particle size of titanium dioxide particles is less than half of the light wave, the maximum scattering effect on the colored light of that wavelength can be produced. This means that the modified conductive titanium dioxide with a particle size less than 40 nm will have stronger light scattering ability, thereby improving its hiding power and tinting strength as a pigment. In addition, due to the increased surface area of the nanoparticles, the reflection and diffuse reflection of light are enhanced, which will further improve the whiteness and gloss of the material. The modified conductive titanium dioxide with a particle size less than 40 nm also shows obvious advantages in terms of dispersibility and stability. The smaller particle size helps to reduce the agglomeration between particles, making the material easier to be evenly distributed in the matrix to form a stable suspension or solution. This good dispersibility is particularly important for applications in industries such as coatings and plastics, because it can directly affect the appearance quality and mechanical properties of the final product.

[0079] In some embodiments, the viscosity of the antistatic coating ≤ 200 cps, the volume resistivity ≤ 10 5 ohm·cm, and the fineness ≤ 10 μm. For the antistatic coating, a viscosity ≤ 200 cps means that the coating has a low viscosity, which makes it easier to spray or brush onto the target surface, ensuring good construction performance. The low viscosity helps to improve the uniformity and coverage effect of the coating, while reducing the formation of bubbles and sagging caused by excessive viscosity. When the volume resistivity ≤ 10 5 ohm·cm, it indicates that this coating has strong conductive ability and can effectively conduct the static charges accumulated on it to the ground or other grounding devices, thus preventing safety accidents caused by static sparks. The fineness of the antistatic coating ≤ 10 μm means that its particles are very fine, and such characteristics can bring various benefits, including but not limited to, enhancing adhesion. The smaller particle size helps the coating to better penetrate into the microporous structure of the substrate surface, thereby strengthening the mechanical interlocking effect between the two and improving the overall adhesion strength. Improving flatness, the fine and uniform particle distribution is conducive to forming a smooth and flat coating surface, reducing the occurrence probability of orange peel effect and other appearance defects. Optimizing durability, since the fine particles can fill more space, the formed coating has higher density and stronger resistance to external environmental factors such as ultraviolet radiation and chemical corrosion.

[0080] The embodiment of the present application also provides a preparation method of an antistatic coating, as Figure 1 shown, including:

[0081] S100. Provide the raw materials in parts by weight of the antistatic coating described in the first aspect and 90 - 100 parts by weight of a low-polarity solvent;

[0082] S200, fully mixing the above raw materials in parts by weight with a low-polarity solvent to obtain a static conductive coating.

[0083] The preparation method of the electrostatic conductive coating provided in the embodiment of the present application, compared with the prior art, has a simple preparation process, low VOC content, good adhesion to the substrate, low resistance value, and the color can be made very white (the conductive carbon tube has low tinting power and is matched with conductive titanium dioxide). It has excellent water resistance after being matched with the topcoat; it can meet the purpose of electrostatic coating, improve the painting of matching color paint and varnish, and reduce the pollution of paint mist to the environment.

[0084] The present application also provides an application of the electrostatic conductive coating provided in the first aspect of the present application, which is applied to the paint coating of automobiles. In the application, the electrostatic conductive coating can also be applied to other coating products, including but not limited to printed circuit boards, housings of electronic equipment, car bodies and parts, medical device housings, home appliance housings, etc. Electrostatic conductive coatings and primers are widely used in the fields of electronics, aerospace, automobiles, petrochemicals, medical treatment, military, industrial equipment, construction, and home appliances, and are mainly used to prevent static electricity accumulation and discharge, and ensure the safety and performance of equipment and products.

[0085] Example

[0086] Example 1

[0087] The present application provides a static conductive coating and a preparation method thereof, wherein the preparation method comprises:

[0088] S100, provide 90kg xylene, 1kg HNBR dispersant, 3kg multi-walled carbon nanotubes, 0.2kg dimethyl silicone oil, 0.1kg polyvinyl alcohol, 1kg modified conductive titanium dioxide, and 2kg acrylic resin;

[0089] S200, fully mixing the above raw materials in parts by weight with xylene to obtain a static conductive coating.

[0090] The dispersant is a homemade HNBR dispersant, and the specific preparation method includes:

[0091] Mixing the nitrile rubber with the solvent to prepare a nitrile rubber solution;

[0092] Preheating the nitrile rubber solution to 120° C. to obtain a preheated nitrile rubber solution, preheating the hydrogen to 140° C. to obtain preheated hydrogen; and simultaneously introducing the preheated nitrile rubber solution and the preheated hydrogen into a tubular reactor;

[0093] The pressure in the tubular reactor was maintained at 5.0 MPa.g and the temperature was maintained at 120°C. The material flowed through the catalyst bed to undergo a hydrogenation reaction to obtain hydrogenated nitrile rubber.

[0094] Among them, the preparation of the modified conductive titanium dioxide is as follows:

[0095] At room temperature, 10 kg of KH-570 is mixed with 150 kg of ethanol and stirred evenly to obtain a mixed solution;

[0096] 90 kg of conductive titanium dioxide is added to the mixed solution. Under stirring, the temperature is controlled at 80 °C, refluxed for 120 min, cooled to room temperature and discharged, filtered through a filter screen, and dried at 60 °C to obtain an intermediate;

[0097] The intermediate is ground in a pulverizer to obtain a silane coupling agent-modified conductive titanium dioxide with a particle size less than 40 nm.

[0098] The performance indexes of the finally obtained electrostatic conductive coating are as follows:

[0099] Viscosity ≤ 200 cps, volume resistivity ≤ 10 5 Ohm·cm, fineness ≤ 10 microns.

[0100] Example 2

[0101] This application example provides an electrostatic conductive coating and its preparation method, and the preparation method includes:

[0102] S100. Provide 100 kg of xylene, 1 kg of HNBR dispersant, 4 kg of multi-walled carbon nanotubes, 0.6 kg of dimethyl silicone oil, 2 kg of polyvinyl alcohol, 4 kg of modified conductive titanium dioxide, and 4 kg of acrylic resin;

[0103] S200. After fully mixing the above raw materials in parts by weight with xylene, an electrostatic conductive coating is obtained.

[0104] Among them, the dispersant is a self-made HNBR dispersant, and the specific preparation method includes:

[0105] Nitrile rubber is mixed with a solvent to prepare a nitrile rubber solution;

[0106] The nitrile rubber solution is preheated to 120 °C to obtain a preheated nitrile rubber solution, and hydrogen is preheated to 140 °C to obtain preheated hydrogen; the preheated nitrile rubber solution and the preheated hydrogen are simultaneously introduced into a tubular reactor;

[0107] Keep the pressure in the tubular reactor at 5.0 mpa.g and the temperature at 120 °C, and the material flows through the catalyst bed for a hydrogenation reaction to obtain hydrogenated nitrile rubber.

[0108] Among them, the preparation method of the modified conductive titanium dioxide is as follows:

[0109] At room temperature, 8 kg of KH-570 is mixed with 150 kg of ethanol and stirred evenly to obtain a mixed solution;

[0110] Add 80 kg of conductive titanium dioxide to the mixed solution. Under stirring, control the temperature at 80 °C, reflux for 120 min, cool down to room temperature and discharge. Filter through a filter screen and dry at 60 °C to obtain an intermediate.

[0111] Grind the intermediate in a pulverizer to obtain silane coupling agent-modified conductive titanium dioxide with a particle size less than 40 nm.

[0112] Example 3

[0113] The embodiment of the present application provides an antistatic coating and a preparation method thereof, wherein the preparation method includes:

[0114] S100. Provide 95 kg of xylene, 1.2 kg of HNBR dispersant, 4 kg of multi-walled carbon nanotubes, 0.5 kg of dimethyl silicone oil, 1.3 kg of polyvinyl alcohol, 3 kg of modified conductive titanium dioxide, and 3 kg of acrylic resin;

[0115] S200. After fully mixing the above raw materials in parts by weight with xylene, obtain an antistatic coating.

[0116] Among them, the dispersant is a self-made HNBR dispersant, and the specific preparation method includes:

[0117] Mix nitrile rubber with a solvent to prepare a nitrile rubber solution;

[0118] Preheat the nitrile rubber solution to 120 °C to obtain a preheated nitrile rubber solution, and preheat hydrogen to 140 °C to obtain preheated hydrogen; simultaneously introduce the preheated nitrile rubber solution and the preheated hydrogen into a tubular reactor;

[0119] Keep the pressure in the tubular reactor at 5.0 mpa.g and the temperature at 120 °C. The material flows through the catalyst bed for a hydrogenation reaction to obtain hydrogenated nitrile rubber.

[0120] Among them, the preparation of the modified conductive titanium dioxide is as follows:

[0121] At room temperature, mix 12 kg of KH-570 with 150 kg of ethanol and stir evenly to obtain a mixed solution;

[0122] Add 85 kg of conductive titanium dioxide to the mixed solution. Under stirring, control the temperature at 80 °C, reflux for 120 min, cool down to room temperature and discharge. Filter through a filter screen and dry at 60 °C to obtain an intermediate;

[0123] Grind the intermediate in a pulverizer to obtain silane coupling agent-modified conductive titanium dioxide with a particle size less than 40 nm.

[0124] Comparative Example 1

[0125] Compared with Example 1, modified conductive titanium dioxide is not added to the components.

[0126] Comparative Example 2

[0127] Compared with Example 1, polyvinylpyrrolidone dispersant is used as the dispersant.

[0128] Comparative Example 3

[0129] Compared with Example 1, the fineness of the antistatic primer obtained is 30 - 50 microns.

[0130] Performance Test

[0131] Test the relevant properties of the coatings prepared in the above examples and comparative examples. The obtained coatings are mixed with a rotor - stator mixer IKA T50 digital ULTRA - TURRAX at a speed of 10,000 rpm for 40 minutes until a uniform suspension is formed, and then further ground. The grinding fineness of the obtained coatings is ≤10 microns, and the viscosity is ≤200 cps. Among them, the grinding fineness in the coatings is measured according to ISO 1524:2020.

[0132] Film Preparation: Add the above - ground primer formulation into a mechanical electrostatic spinning cup. Take a flat plastic sheet without conductive properties, with specifications: 100×100 mm. Use the electrostatic spraying process to evenly spray it on the surface of the polypropylene plastic sheet. The thickness of the film spraying is controlled at 11 μm, and the thickness after drying is about 9 μm. Place it in an 80°C oven for 20 min. Use a Model - 800 surface resistance tester to measure the surface resistance values at different positions of the film, measure three times, and then take the average value. The smaller the measured surface resistance value, the better the conductive performance. Use a Konica Minolta CM - 2600D color difference meter to test the L value of the film. The higher the L value, the better the whiteness of the film. The classification of the coating adhesion grade is usually carried out according to the international standard ISO 2409:2007, with a total of 0 - 5 grades.

[0133] Table 1 Performance Test Results

[0134] Item Volume Resistivity (ohm·cm) L Value Adhesion Time for Stratification to Appear during Static Placement Example 1 <![CDATA[1.2×10 4 > 78 0 Did not appear within one year Example 2 <![CDATA[2.5×10 4 > 81 0 Did not appear within one year Example 3 <![CDATA[3×10 4 > 80 0 Did not appear within one year Comparative Example 1 <![CDATA[6.4×10 5 > 51 1 9 months Comparative Example 2 <![CDATA[7.3×10 6 > 70 2 6 months Comparative Example 3 <![CDATA[7.6×10 5 > 72 1 12 months

[0135] In Comparative Example 1, modified conductive titanium dioxide is not added. Compared with Example 1, its L value decreases significantly, and the conductive performance also decreases; in Comparative Example 2, polyvinylpyrrolidone dispersant is used as the dispersant, and the dispersion performance of carbon nanotube bundles decreases and it is easy to agglomerate, resulting in a significant decrease in conductive performance; in Comparative Example 3, the particle fineness becomes larger, which affects the dispersion uniformity of the primer composition, thus resulting in a decrease in conductive performance and a decrease in the L value.

[0136] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For parts not detailed or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0137] The above-described embodiments are only used to illustrate the technical solutions of the embodiments of the present application, and are not intended to limit them. Although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the embodiments of the present application.

Claims

1. A static conductive coating, characterized in that: It includes the following raw materials in parts by weight: Dispersant 0.5-2 parts; 3-4 parts of carbon nanotubes; Defoaming agent 0.2-0.6 parts; 0.1 to 2 parts of viscosity reducer; 1 to 5 parts of modified conductive titanium dioxide; 1 to 5 parts of acrylic resin.

2. The electrostatic conductive coating according to claim 1, characterized in that: The usage ratio of the carbon nanotubes to the dispersant is (3-4):

1.

3. The electrostatic conductive coating according to claim 1, characterized in that: The carbon nanotubes are multi-walled carbon nanotubes; And / or, the dispersant is a HNBR dispersant; And / or, the viscosity reducer comprises an organic polymer with an inorganic affinity group, wherein the viscosity of the viscosity reducer is 200-300 cps / 25°C and the density is D25≥1.06 g / cm 3 .

4. The electrostatic conductive coating according to claim 1, characterized in that: The preparation method of the dispersant comprises: Prepare a nitrile rubber solution and provide hydrogen; Preheating the nitrile rubber solution to 100° C. to 160° C. to obtain a preheated nitrile rubber solution, and preheating hydrogen to 120° C. to 160° C. to obtain preheated hydrogen; The preheated nitrile rubber solution and the preheated hydrogen are simultaneously introduced into the tubular reactor to react and obtain the dispersant.

5. The electrostatic conductive coating according to claim 1, characterized in that: The preparation method of the modified conductive titanium dioxide comprises: Provide silane coupling agents, organic solvents and conductive titanium dioxide; Mixing the silane coupling agent and the organic solvent to obtain a mixed solution; Add the conductive titanium dioxide to the mixed solution, control the temperature to 70-100° C. under stirring, reflux for 100-150 min, cool to room temperature, discharge, filter and dry to obtain an intermediate; The intermediate is ground to obtain the modified conductive titanium dioxide.

6. The electrostatic conductive coating according to claim 5, characterized in that: The particle size of the modified conductive titanium dioxide is less than 40 nm.

7. The electrostatic conductive coating according to claim 1, characterized in that: The viscosity reducing agent includes one of polyvinyl alcohol, glycerol and boric acid; And / or, the defoaming agent includes one of dimethyl silicone oil, polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycerol ether; And / or, the static conductive coating further comprises 90 to 100 parts by weight of a low polarity solvent.

8. The electrostatic conductive coating according to any one of claims 1 to 7, characterized in that: The viscosity of the electrostatic conductive coating is ≤200cps and the volume resistivity is ≤10 5 Ohm·cm, fineness ≤10 microns.

9. A method for preparing an electrostatic conductive coating, characterized in that: include: Providing parts by weight of the raw material of the electrostatic conductive coating according to any one of claims 1 to 8 and 90 to 100 parts by weight of a low-polarity solvent; The above raw materials in parts by weight are fully mixed with the low-polarity solvent to obtain the static conductive coating.

10. An application of an electrostatic conductive coating, characterized in that: The electrostatic conductive coating is applied to paint surface coating of automobiles.

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